Art of fractionating hydrocarbons



July 3% 1935. w. MENDIUS ART OF FRACTIONATING HYDROCARBONS Filed Nov. 30, 1931 INVENTOR T W T m Wm M mmm,

Patented July 30, 1935 V r "choir-st- ART oFfFI tAcfrIoNATING meanness" William Mendius, Chicagog flllg assignorjto Sin- I clair Refining Company, New

corporation of "Maine York, a r

i Wham iei eaf i eates This invention relates to improvements in fireheated apparatus for distilling petroleum oils with a minimum of decomposition. Oneof the most; widely used conventional typesof apparatus for distilling oil comprises a fire-heated shell still, afractionating tower and a condenser, with connections for conveying vaporsfrom the still to the fractionating tower, for supplying oil to be distilled to the fractionating tower, for conveying admixed condensate and unvaporized oil supplied to the fractionating tower to the still, for conveying vapors from the fractionating tower to the condenserand for discharging resid ual oil from the still. This invention relates particularly to-improvements in this type of ap aratus- 1 {The improved apparatus of the'present invention comprises a fire-heated shell still and a; fractionating tower, a heat exchanging coil ar rangedWit-hin the-shell still and below the noramalliquid level therein, r neans for supplying oil to be distilled to one end of this coil, connections for dischargingoil from the other-end of this. coil to the tower atan intermediate point, con:

nections for conveying oil from the lower end of the, tower to the still, connections for discharg ing vaporized :oil: fromthe upper end, of the tower to a condenser, and connections for discharging-residual oil from the still.

By providing and so arranging the heat exchanging coil through Which the oil to be distilled is passed before it is introduced into the fractionating tower, this oil is brought to a temperature approaching that of the body of oil in the still, in operation, prior to introduction into the tower in a particularly advantageous manner. A part of the burden of vaporization is thus shifted from the still to the tower; that is, more vaporization is efiected in the tower and less vaporization is efiected in the still. This in turn enables the maintenance of a smaller body of oil in the still, in operation. The improved apparatus of the invention thus makes possible a reduction of the temperature to which the oil is heated in the still and a reduction of the average period of time the oil remains in the still. These decreases of time and temperature both tend to minimize decomposition of the oil undergoing distillation. V

The invention will be further described in connection with the accompanying drawing which illustrates, diagrammatically and conventionally, one form of apparatus, and a modification of this form of apparatus, embodying the invention. It will be understood that this further and more detailed description of 1 the invention is notlimited in embodiment a to the particular form of apparatusillustrated. t

- In h cc m any n dr n Fig. 1 is an elevatiorr sectionwith parts broken away of apparatus-embodying the invention, and

' Fig. 2 isa view; corresponding to a transverse section through the still of the apparatus illustratedin Fig. l of a modification.,; t Referring to Big; 1, the apparatus illustrated comprises a fire-heated shell still 3, a fraction-. ating tower-4, aheatexchanging coil 5, a pump 6' for; supplying oil to the heat exchanging coil, 5; a connection lior, discharging oil from the heat exchanging coil Sinto the tower 4, a condenser 8,; a connection 9 .for discharging vaporized ,oil from the. tower 4 to the condenser 8 and a connection- III; for discharging residual oil-from the still 3, the tower: d being connected to the still 3 by avapor line ll and aconnection |2 for conveying oil Iromthe tower- 4 to;t he still-3 The ifractionating; tower I illustrated is" of the type described; in Letters Patent Number 1,683,151, granted to Sinclair.- Refining Company September 4, l,9 28,,-on an application of the late John E. Bell; Any. of-the-conventional forms oflfractionating towers may be used in the combinedapparatusioithe inventiondn place of the particular fractionating tower illustrated in Fig. 1. The so called bubble tower may, for example, be used with advantage.

In the apparatus illustrated, the fractionating tower 4 may be controlled by the regulated introduction, through connection l3, of an appropriate refluxing medium, a part of the distillate discharged from the condenser 8 or a fraction of corresponding character, for example. One or more intermediate fractions may be discharged from the tower 4 above the point at which the oil discharged from the heat exchanging coil 5 is introduced into the tower, through connection It or corresponding connections for example. Connection I5 is provided for initially charging the still.

Steam may be introduced into the body of oil in the still 3, in operation, through a spider connected to connection I6. To promote heat transfer between the body of oil in the still, in operation, and the oil flowing through the heat exchanging coll as well as the heating gases externally contacting with the still, bafiles may be arranged within the still to promote circulation of the body of oil inthe still over the heat exchanging coil and steam jets may be arranged externally contacting with heating gases and over the heat exchanging coil 5, and a connection l9 may be arranged with jets positioned further to promote this circulation, as illustrated.

In operation, an initial body of oil somewhat smaller in volume at the operating temperature than the normal operating body is charged to the still through connection l5, Thestill is then fired and brought on stream in the conventional manner except that the supply of oilto= be distilled through the heat exchanging coil and thence into the tower through connection-T is begun as vapors begin to risethrough the towerl; Oil is initially supplied at a subnormalto the heat exchanging coil 5,-butas the tower 4 reaches operatingconditions and the' introduction of a reflux medium through H is begun, this rate is gradually increased totheopcrating rate. The discharge of residual oil through connection M is=-begun-whenthe-stili reaches operating conditions; or somewhat'before this time if necessary, to maintainanappropriate liquid levelin the still.

The oilto be distilledsupplied-throu'glr the heat exchanging coil 5' is heated int-hatcoil to a temperature approaching that of of oil in the still beforegit is-intrcducedinto the fractionating tower 4-. the heat" surface of the heat-exchanging coiH isincreaaedand the circulation of the of oilin the-still- 3- is augmented, the temperature to which the oil passing through the" heat exchanging coil!) is heated approaches that of the'bodyof oil 'in the still more-and more closely; Asft'he thus heated oil is introduced into the rractlonating tower 4, a larger part ofit is 'vapcrizedanda oil; maintained in the still reduces the average period of time the oil is in the still which also,

reducing the time at which the oil is at elevated temperature, further reduces decomposition.

I claim: 1. In combination in fire-heated apparatus for distilling oil with a minimum of decomposition,

a fire-heated shell still, a fractionating tower and a vapor connection between said still and said tower, a heat exchanging coilarranged withirrthe shell still and below the normal liquid level therein, means for supplying oilto be disto one'end of said coil, connections for discharging oilfrom the other end of said coil into the tower at an intermediate point, connections for-conveyingoil from the lower end of the tower to the-still, connections for discharging vaporized oilfrom the upper endof the tower to a condenser, and connections for discharging residual oii from the still.

2. In con-'lbination in fire-heated apparatus for distilling oil with a minimumof decomposition, a; fire-heated shell still, a fractionating tower and a vapor connection between said stilland said tower, a heat exchanging coil arranged within the shell still and below the normal liquid level therein, means for supplying oil tobe distilledto one end of said: coil, connections for discharging oil from the other end of said coil into the tower at an intermediate point, means for introducing a refluxing medium into the tower at a higher point, connections for conveying oil from the lower end of the tower to'the still, connections for discharging vaporized oilfrom' the upperend of the tower to a condenser, andconnations for discharging residual oil from the still 'WILLIAM MENDIUS. 

